Carl v



N IiTE CARL v. PE'IRAEUS,

STATES or JOPLIN, MISSOURI, ASSIGNOR TO OLIVERH.

PICHER, OF SAME PLACE.

METHOD OF SMELTING GALENA.

SPECIFICATION forming part of Letters Patent No. 588,289, dated August17, 1897.

Application filed April '7, 1896. Serial No. 586,587. (No specimens.)

To all whom it may concern:

Be it known that I, CARL V. PETRAEUS, a citizen of the United States,residing in J oplin, in the county of Jasper and State of Missouri, haveinvented a certain new and useful Improvement in Methods of SmeltingGalena, of which the following is a true and exact description.

My invention relates to the smelting of galena ore, and has for itsobject to reduce substantially all the lead contents of such ore tometallic form and at a low cost of treatment.

In my former patent, No. 556,691, dated March 17, 1896, I have describeda method of treating galena ore in which the 'ore is first treated in anopen-hearth blast-furnace, with the result of producing a certainquantity of metallic lead, a certain quantity of lead f ume; consistinglargely of lead sulfid, and slag and cinder both rich in lead. The fumescollected from this furnace are cintered together and resmelted and themetal-bearing slag and cinder are also resmelted in a low-cupolablastfurnace, the fume driven oif from this furnace consisting,essentially, of lead sulfate and lead oxid, being agglomerated bypressure or cementation and again smelted to reduce them to metalliclead. In the treatment of my said former patent it was necessary toprovide separate screen systems for the fumes obtained from thelow-cupola blast-furnace and those obtained from the open-hearthfurnace, because the'fume obtained from the openhearth furnace,consisting largely of lead sulfid, can be cintered together in conditionfor charging into a furnace by simply igniting it, while the fume fromthe low-cupola furnace cannot be cintered in this way, but requirescomparatively expensive modes of treatment to fit it for use in afurnace, and it has been found that the mixture which would result fromcollecting the fumes from both furnacesin one screen system wouldrequire to be treated in the same manner as the fume from the low-cupolafurnace, which treatment is more expensive and less satisfactory inresult which shall consist largely of lead sullid and be of a characterwhich will permit it to cinter by ignition, thus enabling me to providea single screen system for all the fumes generated in the treatment ofthe ore as well as to obtain a cintered fume of the best character forfurther furn ace treatment from the entire mass of fume produced.

In the so-called low-cupola blast-furnace referred to in my formerpatent, also technically known as a slag hearth-furnace, the surface ofthe charge and the top of the furnace are both very hot and of anoxidizing character, so that any lead sulfid which may be thrown offfrom the furnace in the form of fume is oxidized in the top of thefurnace and passes to the lines and screen system as lead sulfate andlead oxid. In an ordinary stackfurnace, on the other hand, it has beenfound impracticable to treat material so rich in leadand sulfur as theslag-cinder and agglomerated fume from the open-hearth blast-furnace,because the fume generated in such a furnace forms scal'folds, as theyare called, upon the walls of the furnace so rapidly as to interferevery seriously with the operation of the furnace and because that fromthe airpressure necessarily used in the ordinary stack-furnace there isproduced alarge quantity of lead matte, which is highly undesirable andwhich can only be avoided by the use of a very large quantity of ironflux, which is not always available, and if available is apt to beexpensive.

NowI have discovered that the rich loadbearing material, which inaccordance with my former patented process was treated in the low-cupolablast-furnace, can be smelted in such a Way as to produce a fumelargelyconsisting of lead sulfid without serious trouble from the formation ofscaffolds or crusts in the furnace and without producing anyconsiderable amount of lead matte by smelting it in a stack-furnacethe-height and air-pressure of which are so regulated that the top ofthe charge and top of the furnace will be at a temperature too low tocause the oxidation of lead-sulfid fumes and in which the mini mumair-pressure is maintained-that is to say, the furnace is made as low aspracticable consistent with the desired low temperature of the top ofthe charge-and the principal reason for this is that by constructing andoperating a furnace as above described I keep the smelting-zone of thefurnace at a comparatively low temperature compared with the temperatureused in stack-furnaces, and the formation of the lead matte appears onlyto occur when the temperature of the smelting-zone is high.

In practice I have constructed my furnaces with aheightof about fivefeet from the twyers to the top of the charge and have used an airblastwhich gives in this furnace a pressure of from two to three inches ofwater, and this furnace I have found to give excellentresults, producinga fume rich in lead sulfid and substantially no lead matte. The minimumheight of the furnace charge should not be less than four feet, nor isit advisable to construct a furnace for my purposes the charge in whichwould exceed six feet.

My new method of smelting galena ore con sists, therefore, in firsttreating the galena in the open-hearth blast-furnace, as in myformerpatented process, and collecting the fumes from this furnace andcentering them by ignition. Then I take the slag and cinder from theopen-hearth furnace together with the cintered fume from the open-hearthfurnace and the cintered fume prepared, as described, from the fume ofthe second furnace treatment and smelt these materials in a furnace ofthe construction above describedthat is to say, one having a temperatureat the top of the charge too low to cause the oxidation of sulfid fumeand a low blastpressnre-and I collect and einter by ignition the fumefrom this furnace, charging the centered fume again into thestack-furnace.

s As the fume from both furnace treatments is of substantially the samecharacter, I am enabled to use a single-screen system for collecting thefume from both treatments, which is a considerable source of economy incost of plant, and whether the fume is collected in one or two screensystems it is in any case of a better and more suitable character forfurther furnace treatment than where the lowcupola furnace of my formerpatented process is used.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent, is

The method of smelting galena which consists in first treating the orein an open-hearth blast-furnace and collecting the lead fume containinga large percentage of lead sulfid driven off therefrom, treating themetal-bearing slag of the open-hearth furnace and cintered fume in astack-furnace in which the temperature at the top of the furnace ismaintained at so low a point as to prevent the oxidation of thelead-sulfid fume generated in the furnace, collecting the fumecontaining a large percentage of lead suliid drawn 01f from thestack-furnace, agglomerating the fume from both furnaces by cinteringand smelting it in the stack-furnace aforesaid together with the slagfrom the open-hearth f urnaee.

- CARI, V. PETRAEUS.

\Vitnesses:

A. E. SPENCER, GALEN SPENCER.

